Jimmy's ideal job is assistant, he didn't like the responsibility of having everything depending on him (work with his long term mate).
You can't deny McNamara has a decent grasp of the game but a half time savaging from him must be like being licked to death by a toothless Labrador. The only aggressive thing I ever saw him do was drill a penalty kick for touch low and hard into the Threepenny Stand at the Boulevard in response to an hours 'FC Reject' chanting...
Having a Jimmy in there to help 'deliver' the message can only be a good thing.